Adding hot memory to a virtual machine fails

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• When attempting to add hot memory to a virtual machine, the option is greyed out.
• Unable to add hot memory to a virtual machine.
• Adding hot memory to a virtual machine fails.
  

Environment

VMware ESX 4.1.x
VMware ESX 4.0.x
VMware ESXi 4.0.x Embedded
VMware vSphere ESXi 5.0
VMware vSphere ESXi 5.1
VMware ESXi 4.0.x Installable
VMware ESXi 4.1.x Installable
VMware ESXi 4.1.x Embedded

Resolution

To resolve this issue:

1. Ensure the host has the required license Hot Pluggable Virtual Hardware:
   1. Log in to the vSphere Client and select the ESX host.
   2. Click the Configuration tab.
   3. Select Licensed Features.
   4. Verify if you have Hot Pluggable Virtual Hardware.
      
      
2. Ensure the Virtual Machine has the options enabled:
   1. Log in to the vSphere Client.
   2. Right-click on the virtual machine.
   3. Navigate to Edit Settings > Options > Memory/CPU HotPlug.
   4. Select Enable Memory Hot Add for this Virtual Machine.

Note: It is equally important that the guest operating system supports the hot add feature. To determine if it does, see the VMware Hardware Compatibility List (choose Guest OS from the What are you looking for dropdown). The virtual hardware section under the Guest OS should read supported.